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Federer, Nadal disagree with Djokovic on Troicki's doping case

Roger Federer stands by the rules when it comes to doping tests. (BEN STANSALL/AFP/Getty Images)

LONDON -- Novak Djokovic's scathing comments on tennis' anti-doping authorities have dominated conversation at the ATP World Tour Finals this week. The world No. 2 said he had lost all faith in the anti-doping system after the way fellow Serb Viktor Troicki's punishment was handled for failing to provide a requested blood sample.

Djokovic called the ruling to reduce but not eliminate Troicki's ban "a total injustice" because no one explained to Troicki the consequences of not giving the requested sample immediately. The doping control officer's "negligence" and "unprofessionalism" has cost the 27-year-old Troicki a year of his career, according to Djokovic.

Roger Federer and Rafael Nadal, however, both stand by the rules.

"Overall, I trust the [anti-doping] system," Federer said after defeating Richard Gasquet 6-4, 6-3 on Thursday. "I think they're all very professional.

"I do believe that when you are requested for a sample, you have to give the sample," Federer continued. "It doesn't matter how bad you feel. I'm sorry. The test the next day is not a test anymore because what could have happened overnight, you know? I don't believe anything."

Nadal was sympathetic with Troicki's plight but agreed with Federer.

"We have rules," he said after his win over Stanislas Wawrinka on Wednesday. "We can like [the rules] or not, but we have rules. I am very sorry for Viktor because I believe 100 percent in him. Probably the doctor make the mistake. But he knows that he has to pass the doping [test]."